[3주차] 장고 활용한 API서버 만들기 (2)

🙂 View와 Templates

Django에서는 Model을 통해 DB 정보를 저장.

View에서는 그 Model을 활용.

✔  polls/views.py

from .models import *
from django.shortcuts import render

def index(request):
    latest_question_list = Question.objects.order_by('-pub_date')[:5]
    context = {'first_question': latest_question_list[0]}
    return render(request, 'polls/index.html', context)

✔  Django Shell

>>> from polls.models import *
>>> Question.objects.order_by('-pub_date')[:5] 
>>> print(Question.objects.order_by('-pub_date')[:5].query) 
SELECT "polls_question"."id", "polls_question"."question_text", "polls_question"."pub_date" FROM "polls_question" ORDER BY "polls_question"."pub_date" DESC LIMIT 5

✔  polls/templates/polls/index.html

<ul>
    <li>{{first question}}</li>
<ul>

---

🙂 Templates에서 제어문 사용

✔  polls/templates/polls/index.html

{% if questions %}
<ul>
  {% for question in questions %}
  <li>{{question}}</li>
  {% endfor %}
</ul>
{% else %}
<p>no questions</p>
{% endif %}

✔  polls/views.py

from django.http import HttpResponse
from .models import *
from django.shortcuts import render

def index(request):
  latest_question_list = Question.objects.order_by('-pub_date')[:5]
  context = {'questions': latest_question_list}
  return render(request, 'polls/index.html', context)

def some_url(request):
  return HttpResponse("Some url을 구현했습니다.")

---

🙂 상세(detail) 페이지 만들기

✔  polls/views.py

def detail(request, question_id):
    question = Question.objects.get(pk=question_id)
    return render(request, 'polls/detail.html', {'question': question})

✔  polls/urls.py

from django.urls import path
from . import views

urlpatterns = [
    path('', views.index, name='index'),
    path('some_url', views.some_url),
    path('<int:question_id>/', views.detail, name='detail'),
]

✔  polls/templates/polls/detail.html

<h1>{{ question.question_text }}</h1>
<ul>
{% for choice in question.choice_set.all %}
    <li>{{ choice.choice_text }}</li>
{% endfor %}
</ul>

---

🙂 상세(detail) 페이지로 링크 추가하기

✔  polls/urls.py

from django.urls import path 
from . import views  

app_name = 'polls'

urlpatterns = [     
    path('', views.index, name='index'),
    path('some_url', views.some_url), 
    path('<int:question_id>/', views.detail, name='detail'),     
    
]

✔  polls/templates/polls/index.html

{% if questions %}
<ul>
    {% for question in questions %}
         <li><a href="{% url 'polls:detail' question.id %}">{{ question.question_text }}</a></li>
         
    {% endfor %}
<ul>
{% else %}
<p>no questions</p>
{% endif %}

---

🙂 404 에러 처리

✔  polls/views.py

from models.py import *
from django.http import HttpResponse
from django.http import Http404
from django.shortcuts import render , get_object_or_404

...
def detail(request, question_id):
    """
    try:
        question = Question.objects.get(pk=question_id)
    except Question.DoesNotExist:
        raise Http404("Question does not exist")
    """
    question = get_object_or_404(Question, pk=question_id)
    return render(request, 'polls/detail.html', {'question': question})

---

🙂 폼

CSRF: Cross-site request forgery 사이트 간 요청 위조

인증된 사용자가 웹 애플리케이션에 특정 요청을 보내도록 유도하는 공격 행위

- CSRF 토큰을 통해 방지

✔  polls/views.py

def vote(request, question_id):
    question = get_object_or_404(Question, pk=question_id)
    try:
        selected_choice = question.choice_set.get(pk=request.POST['choice'])
    except (KeyError, Choice.DoesNotExist):
        return render(request, 'polls/detail.html', {'question': question, 'error_message': '선택이 없습니다.'})
    else:
        selected_choice.votes += 1
        selected_choice.save()
        return HttpResponseRedirect(reverse('polls:index'))

✔  polls/urls.py

from django.urls import path 
from . import views

app_name = 'polls'
urlpatterns = [
    path('', views.index, name='index'), 
    path('<int:question_id>/', views.detail, name='detail'),
    path('<int:question_id>/vote/', views.vote, name='vote'),  
]

✔  polls/templates/polls/detail.html

<form action="{% url 'polls:vote' question.id %}" method="post">
    {% csrf_token %}
    <h1>{{ question.question_text }}</h1>
    {% if error_message %}
    <p><strong>{{ error_message }}</strong></p>
    {% endif %}
    
    {% for choice in question.choice_set.all %}
        <input type="radio" name="choice" id="choice{{ forloop.counter }}" value="{{ choice.id }}">
        <label for="choice{{ forloop.counter }}">
            {{ choice.choice_text }}
        </label>
        <br>
    {% endfor %}

<input type="submit" value="Vote">
</form>

---

🙂 에러 방어하기

✔  polls/views.py

서버 상의 이유로 선택지가 나오지 않을 경우

def vote(request, question_id):
    question = get_object_or_404(Question, pk=question_id)
    try:
        selected_choice = question.choice_set.get(pk=request.POST['choice'])
    except (KeyError, Choice.DoesNotExist):
        return render(request, 'polls/detail.html', {'question': question, 'error_message': f"선택이 없습니다. id={request.POST['choice']}"})
    else:
        selected_choice.votes += 1
        selected_choice.save()
        return HttpResponseRedirect(reverse('polls:results', args=(question.id,)))

 

다른 서버에서 동시에 같은 선택지를 고를 경우

from django.urls import reverse
from django.db.models import F

def vote(request, question_id):
    question = get_object_or_404(Question, pk=question_id)
    try:
        selected_choice = question.choice_set.get(pk=request.POST['choice'])
    except (KeyError, Choice.DoesNotExist):
        return render(request, 'polls/detail.html', {'question': question, 'error_message': f"선택이 없습니다. id={request.POST['choice']}"})
    else:
        # A서버에서도 Votes = 1
        # B서버에서도 Votes = 1 
        selected_choice.votes = F('votes') + 1
        selected_choice.save()
        return HttpResponseRedirect(reverse('polls:index'))

---

🙂 결과(result) 조회 페이지

✔  polls/views.py

from django.shortcuts import get_object_or_404, render

...
def vote(request, question_id):
...
    else:
        selected_choice.votes = F('votes') + 1
        selected_choice.save()
        return HttpResponseRedirect(reverse('polls:result', args=(question.id,)))

def result(request, question_id):
    question = get_object_or_404(Question, pk=question_id)
    return render(request, 'polls/result.html', {'question': question})

✔  polls/templates/polls/result.html

<h1>{{ question.question_text }}</h1><br>
{% for choice in question.choice_set.all %}

    <label>
        {{ choice.choice_text }} -- {{ choice.votes }}
    </label>
    <br>
{% endfor %}

✔  polls/urls.py

from django.urls import path
from . import views

app_name = 'polls'
urlpatterns = [
    path('', views.index, name='index'),
    path('<int:question_id>/', views.detail, name='detail'),
    path('<int:question_id>/vote/', views.vote, name='vote'),
    path('<int:question_id>/result/', views.result, name='result'),
]

---

🙂 Django Admin 페이지 커스터마이징

✔  polls/admin.py

from django.contrib import admin
from .models import Choice, Question

admin.site.register(Choice)

class ChoiceInline(admin.TabularInline):
    model = Choice
    extra = 3


class QuestionAdmin(admin.ModelAdmin):
    fieldsets = [
        ('질문 섹션', {'fields': ['question_text']}),
        ('생성일', {'fields': ['pub_date'], 'classes': ['collapse']}),        
    ]
    readonly_fields = ['pub_date']
    inlines = [ChoiceInline]

admin.site.register(Question, QuestionAdmin)

---

🙂 Django Admin 목록 페이지 커스터마이징

✔  polls/models.py

import datetime
from django.db import models
from django.utils import timezone
from django.contrib import admin


class Question(models.Model):
    question_text = models.CharField(max_length=200, verbose='질문')
    pub_date = models.DateTimeField(auto_now_add=True, verbose='생성일')  

    @admin.display(boolean=True, description='최근생성(하루기준)')
    def was_published_recently(self):
        return self.pub_date >= timezone.now() - datetime.timedelta(days=1)
    
    def __str__(self):
        return f'제목: {self.question_text}, 날짜: {self.pub_date}

✔  polls/admin.py

from django.contrib import admin
from .models import Choice, Question

admin.site.register(Choice)

class ChoiceInline(admin.TabularInline):
    model = Choice
    extra = 3


class QuestionAdmin(admin.ModelAdmin):
    fieldsets = [
        ('질문 섹션', {'fields': ['question_text']}),
        ('생성일', {'fields': ['pub_date'], 'classes': ['collapse']}),        
    ]
    readonly_fields = ['pub_date']
    inlines = [ChoiceInline]
    list_filter = ['pub_date']
    search_fields = ['question_text', 'choice__choice_text']
    
admin.site.register(Question, QuestionAdmin)